Australia's largest salmon producer Tassal is heading for foreign ownership after shareholders voted in favour of a $1.1 billion takeover by Canadian company Cooke Aquaculture.
Almost 97 per cent of Tassal shareholder votes were in favour of the $5.23 per share takeover bid, it was confirmed after a company meeting in Melbourne on Thursday.
The takeover has been approved by the Foreign Investment Review Board, but requires final court approval at a hearing in early November.
Tassal chief executive Mark Ryan previously said Cooke was a "natural fit" and the acquisition would fast-track Tassal's goal of being one of the world's most transparent and sustainable protein producers.
Tasmania's two other major salmon farmers are owned by overseas companies, with New Zealand's Sealord buying Petuna in 2020 and Brazilian-owned JBS purchasing Huon Aquaculture in 2021.
Conservationists including the Bob Brown Foundation have raised concerns about Cooke's environmental track record and potential expansion in Tasmania.
In a legal settlement with the Washington Department of Ecology in 2019, the company paid a $US332,000 ($A518,000) penalty after the collapse of a pen released 250,000 non-native fish.
In 2019 it was also fined by the Maine Department of Environmental Protection over multiple violations at farming sites in the US state, including having too many fish in pens.
"Despite a growing global movement of salmon farming being banned or phased out, Tasmania is opening the door to this environmental vandal," Bob Brown Foundation campaigner Alistair Allan said.
Several activists rallied outside Tassal's meeting in Melbourne.
The Tasmanian Alliance for Marine Protection has written an open letter to Premier Jeremy Rockliff claiming the state's environmental watchdog lacks the resources to adequately monitor Cooke.
The state government backs Cooke's takeover, Liberal minister Guy Barnett said.
"What is important for this government is our support for a sustainable, highly regulated salmon industry in Tasmania and the jobs that it delivers," he said.
The Global Salmon Farming Resistance has criticised the takeover in full-page advertisements published in major newspapers across the country.
The group urges Tasmania's government to develop a plan to reduce inshore fin-fish farming sites, in line with a recommendation from a recent Legislative Council report into the state's aquaculture industry.
Tassal, founded in 1986, is the largest producer of Tasmanian-grown Atlantic salmon.
A 10-year salmon plan being developed by the Tasmanian government for implementation in 2023 includes a shift to land-based and deepwater fish farming.